Handling dependencies

A function is allowed to use external Node.js modules as well as local
data. Dependencies in Node.js are managed with npm and expressed in a
metadata file called package.json. The Cloud Functions
Node.js runtimes generally support installing using npm or
yarn.

To specify a dependency for your function, add it to your package.json file.

TypeScript

Including local Node.js modules as part of your deployment package

You can also include local Node.js modules as part of your function. You can
achieve this by declaring your module in package.json using the
file: prefix. In the
following example, mymodule refers to your module name and mymoduledir is
the directory containing your module:

{
"dependencies": {
"mymodule": "file:mymoduledir"
}
}

The code for this local module should not be in your node_modules folder. You
can simply store it at the root of your function's directory.

Note: The Firebase CLI ignores the local node_modules folder when deploying
your function.

Using npm to install Node.js modules locally

The easiest way to install a Node.js module locally is to use the npm install
command in the folder containing your Cloud Function. For instance, the
following command adds the uuid module:

npm install uuid

This combines two steps:

It marks the latest version of the module as a dependency in your
package.json file. This is very important: Cloud Functions only
installs modules that are declared in your package.json file.

It downloads the module into your node_modules directory. This lets you
use the module when developing locally.

Additional steps for TypeScript

TypeScript helps you most when you use libraries that have type information.
This lets TypeScript catch syntax errors and lets editors give you better
autocomplete suggestions. Some libraries, like firebase-admin and
firebase-functions, ship with TypeScript definitions included.

Many libraries do not provide their own TypeScript definition. The
DefinitelyTyped project
provides community-maintained definitions for the most popular node libraries.
DefinitelyTyped publishes these definitions under the same NPM package name, but
inside the "@types" organization. For example, you can install the type
information for the uuid library with the following:

npm install @types/uuid

As you become more familiar with TypeScript, you might find yourself combining
both installs:

npm install uuid @types/uuid

Type dependencies should be the same kind as the library dependency. For
example, you should not save uuid as a normal dependency and @types/uuid as
a dev dependency or peer dependency.

Loading Node.js modules

Use the Node.js
require()
function to load any Node.js module you have installed. You can also use the
require() function to import local files you deploy alongside your function.

If you are writing functions in TypeScript, use the
import
statement in the same way to load any Node.js module you have installed.

Using private modules

In order to use a private npm module, you must provide credentials (auth
token) for the npm registry in a .npmrc file located in the function's
directory. The npm documentation explains how to create custom read-only
access tokens. We discourage using the .npmrc file created in the home
directory because it contains a read-write token. Write permissions are not
required during deployment, and could pose a security risk.

Do not include the .npmrc file if you're not using private repositories,
as it can increase the deployment time for your functions.